The present invention relates to guide rail assemblies for effecting limited displacement of a vehicle seat in a longitudinal direction within the vehicle. Commonly known assemblies of this type include first and second interleavable guide rail means which are individually bolted to the vehicle seat and to the vehicle floor, respectively. In such designs, a plurality of aligned apertured regions are provided in adjacent transverse walls of the interleaved guide rail elements. In one known design of this type, exemplified in U.S. Pat. No. 3,790,234, a blocking arrangement disposed outside the guide rail assemblies is mounted for transverse movement inwardly toward the apertured regions in the interleaved guide rail elements to selectively lock the first and second guide rail means against relative movement when the apertures are aligned. In such designs, the movable guide rail portions may include a hollow, substantially closed profile surrounded by a substantially U-shaped fixed rail element, such closed profile being far better to absorb the increased loads characteristic of modern, power vehicle seat applications than previous designs.
The disadvantages of known assemblies of this type include their relative bulkiness, caused principally by the necessity of providing space for the mounting and movement of the external blocking member. Additionally, since such external member lies relatively unprotected within the vehicle, the operation of the guide rail assembly and particularly its latching in a desired position of the seat is subject to contamination by dirt and to mechanical malfunction.